Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true and non-destructive behavior, so the safety profile is covered. The description goes further by stating the tool never takes payment, that the traveler pays at the confirmation screen, and that the QR code arrives by email and in My Page after payment — meaningful behavioral context beyond the structured fields.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three short sentences, front-loaded with what the tool returns, then the payment and post-payment behavior. Every sentence carries information. The opening phrase 'Link straight to the final confirmation screen' is slightly clipped but efficient.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

There is no output schema, so the description must convey what the agent gets back; it describes the link, the payment boundary, and the QR code delivery. With read-only/idempotent annotations covering safety, this is close to complete, though it never describes the link's format or expiry.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 67%: lang and days are well documented in the schema, but the required plan_id has no description. The description references 'this plan' but adds no parameter-level detail (e.g., format of plan_id, when days is needed), so it neither compensates for the gap nor abuses the reader. Baseline 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the resource: a link to the final confirmation/checkout screen for a specific plan. The implied verb (return a purchase link) is unambiguous and distinguishable from siblings like get_plan or estimate_data. It stops short of explicitly naming an alternative, but the purpose is immediately graspable.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It conveys that the traveler pays at the destination and that no payment is taken here, which implies a pre-purchase context. However, there is no explicit when-to-use guidance, no prerequisites, and no reference to the sibling tools (get_plan, estimate_data, recommend_plan) that an agent would need to route between.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.